


a bittersweet thirst

by alexanderlightweight



Series: Words of October 2019 [17]
Category: Shadowhunters (TV)
Genre: Alternate Universe - Canon Divergence, Light Bondage, Lorenzo Rey's inferior magic, M/M, Marking, Possessive Magic, Protective Magnus Bane, Semi-Sentient Tentacles, Tentacles, Tentacletober
Language: English
Status: Completed
Published: 2019-10-11
Updated: 2019-10-11
Packaged: 2020-12-07 20:57:07
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,180
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/20982257
Author URL: https://archiveofourown.org/users/alexanderlightweight/pseuds/alexanderlightweight
Summary: Magnus knew that magic.  He knew it more intimately than he had ever wanted to know another’s powers and he hated it.The feel, the taste, the capability of it, all if it he detested.It had been a lifeline when he’d needed one but even a man dying of thirst will drink saltwater and think it sweet.





	a bittersweet thirst

**Author's Note:**

  * For [lynne_monstr](https://archiveofourown.org/users/lynne_monstr/gifts).

> This is for tentacletober prompt 8: Tied up by Tentacles because I am going out of order. 
> 
> Also, I blame [lynne_monstr](https://archiveofourown.org/users/lynne_monstr/pseuds/lynne_monstr) tumblr because this was supposed to be about the complications and heavy emotions involving Alec being tied to the same magic that nearly killed Magnus. Instead it became more about jealous semi-sentient tentacles and tentacle hickeys. yay!!
> 
> This was also supposed to be the plot for the 'first time tentacles prompt' but I got distracted when writing that one too so... I just don't stay on task very well apparently.

“What’s wrong?” Alec asked and Magnus tried not to shudder at the feeling of  _ bad-toxic-awful  _ that crept into him from their embrace.

“Nothing’s wrong,” he promised, “my magic is just a bit,  _ temperamental  _ at the moment.”

“But it’s yours. You have it back and it won’t hurt you?” And there was something desperate and fervent in Alec’s voice as he checked.

“I’m fine Alexander, it’s mine. Completely and wholly and more so than it has been oh, for centuries even.” Magnus reassured him, patting his shoulder and smoothing down the fabric of his shirt.

There had always been a small part of Magnus left in Edom. It had been the price he’d paid to bind his father there and keep him from leaving. Magnus had never mentioned it, not to anyone for centuries because well… he’d had no intention of returning to Edom and to lose just a small piece of himself and his identity had always seemed such a small price when it meant being free of his father.

Now, having suffered the absolute loss of his magic, he agreed. The time without his father had been worth the separation, no matter that he did feel better having them back. The moment he’d set foot in Edom his tentacles had wreathed him in the dark, red of Edom’s light, excited to be back with him but also stronger and more  _ other _ than he remembered them being. They had been in Edom for almost too long, chaining Asmodeus down and pulling the Prince back when he tried to cross over but now, now they were Magnus’ again.

They were his and they did not like what they could feel. 

Oh, the warmth of Alec in his arms was lovely and it would always be something he enjoyed and cherished. The buzz of someone else’s magic under Alec’s skin? The recognizable and putrid feel of Lorenzo’s magic flowing through  _ Magnus’ _ fiancé?  _ That _ was intolerable.

Alec knew now about the tentacles but he did not know how much they wanted to know him. Or how much they seethed in annoyance that Alec bore the claim of another, the yellow scales that occasionally dusted his knuckles or brushed against his runes made Magnus lips curl in disdain even as his tentacles coiled, ready to strike.

“I don’t think they like me,” Alec admitted softly. He’d been wary but willing enough when Magnus had brought his glamour down but when he’d reached out to touch his fingers had been smacked aside and Magnus knew he’d been stung, more emotionally than physically. 

“They’re just,” Magnus hesitated, he knew how it felt to be rejected, even a small bit, by someone you loved so very much and hated that Alec felt that way. However, he didn’t know how to explain the misunderstanding without sounding ungrateful. Alec had only bound himself to Lorenzo so he could survive in Edom. He had come with the intention of binding himself to Magnus and  _ staying _ with him, so being upset seemed trite and ungracious when compared to the bigger picture. 

“It’s alright, we’ll figure it out. Whatever it is, right?” And the question in Alec’s words and the hope in his eyes meant Magnus had to surge forward and clench his fingers in Alec’s shirt as he dragged him close for another, toe-curling and life affirming kiss.

“Of course we will,” he promised, “we’re together, we have our home back and everything will be fine.”

“You sure you don’t want to come with me? I won’t be long.” Alec promised, clearly not wanting to leave but knowing he needed to go.

“I have a few things to do here,” Magnus said, “but I’m not going anywhere.” 

Alec left with another, soft kiss and quick wave to Magnus’ tentacles, indecision on his face as he ducked past them and out the door. Magnus narrowed his eyes the moment Alec left the loft and he side-eyed his wary tentacles. 

“We,” he said sternly, “will be having a very important talk.” He paused and gave the loft a critical once-over, “first however. A bit of redecoration is in order. This place is abhorrent.” 

-

The loft was restored to its former comfort and updated glory by the time Alec came home. What hadn’t been portaled to Lorenzo’s mansion had been tossed and Magnus was relaxing from a job well-done with a wonderfully chilled martini. There was a rather elegant stir stick he didn’t remember having but then again, he had brought many things of storage to redecorate with. 

“Alexander,” Magnus said in greeting and oh but to say his name and know that he would answer, to have him so close again and Magnus’. It was a joy and privilege he would never take for granted, not after having lost it. Magnus could have done without the blood on Alec’s knuckles and cheek but he was whole and mostly safe and  _ home _ .

“Sorry, I would have used an iratze if I could.” Alec said sheepishly, “my stele works well enough but sometimes the magic and runes fight with what works better. The runes didn’t work well in Edom because of the warping of demonic plane. Here though, they seem to be in a constant battle with each other.” He shrugged, as though the move didn’t make him wince and Magnus watched as acrid yellow climbed playfully up his shoulders and pressed tiny swirls of magic against his skin.

Magnus knew that magic. He knew it more intimately than he had ever wanted to know another’s powers and he  _ hated _ it. 

_ The feel, the taste, the capability of it, all if it he detested. _

It had been a lifeline when he’d needed one, but even a man dying of thirst will drink saltwater and think it sweet.

Magnus had been dying of thirst and by Edom, how his body had burned from the poison but he’d relished the destruction of himself just for the feel of minute relief it had brought. To see it, to have to watch as it coiled in Alec’s body and pressed against his skin, filled him with a nearly incandescent rage.

It was an unconscious choice, to act. Magnus prided himself on his control but while meeting Alec had been worth every hardship, all the battles of the last few months had worn heavily on his self-restraint.

In a moment Alec was trapped against the wall by tentacles and blue fire that ignited angrily in the air but fell and extinguished delicately against his skin. His eyes widened, glowing dark in the wake of Magnus’ outburst. 

“Magnus?” He asked and then grunted, back against the wall when a tentacle pressed against his lips to shush him.

“It’s all over you,” Magnus finally said, “in you. It’s practically taunting me,” he admitted and Alec’s throat jumped, his Adams apple bobbing under a sickly yellow glow. 

“Lorenzo’s magic?” Alec asked gently, “Is this because it hurt you, when he transfused it?”

“It’s because,” Magnus said softly, “it’s an intimate affair. It was his magic but my core, the magic was slowly becoming mine but yours is an angelic core, Alexander. The magic in you will always belong to the person connected to it and that means,” Magnus paused and gently stroked his thumb over Alec’s cheekbone. “That means he’s here.” He brought up his other and pressed it over Alec’s chest, fingertips pressing into the skin above Alec’s heart. For a moment he wished he could reach in and hold it, cup the precious treasure beating in Alec’s chest in his palm.

“So we find a way to make it wear off quicker?” 

“Do you trust me?” Magnus asked and it felt like such a delicate question, with Alec surrounded by all of him but it only earned him a sweet, confident and calm smile.

“Of course,” and Alec moved, arms straining against the tentacles pinning him to the wall until he huffed, letting himself flop back against the brick. “I’d kind of like to hug you right now but I trust you. However you need to get rid of the magic, I trust you.” 

No sooner had he said that then Magnus’ tentacles were pressing close to him, a few tugging his shirt from his pants and then sliding up along his skin. Magnus could feel them. It was like running his hand over Alec’s skin and when the texture changed, from smooth, seamless tentacles to ones with suckers that pressed delicately, invitingly to Alec’s skin, Magnus shuddered.

They pulled it from him, drank it from his core in persistent, and desperate fervor. Magnus licked his lips, relief thick at the back of his throat at the realization that soon Alec would be free. Lorenzo had no place in their life and certainly no place being so intimately connected to Magnus’ fiancé.

Magnus hands shook, just a little but enough so that two of his tentacles took over and he pressed his palms against Alec’s shoulder as they unbuttoned his shirt.

Alec’s chest was heaving, his breath coming in low, quick rasps and his eyes half lidded, a grimace of pleasure-pain on his brow and Magnus pressed a kiss to his bared neck. 

“Soon,” he promised, “you’re doing so good. They’re almost done.”

Alec nodded, chin bumping against Magnus ear and then he grunted, fingers clutching on nothing and Magnus hurried to offer his own hands. Biting down on Alec’s neck when his fingers were gripped a little too tightly and he pushed forward, wanting to be of as much comfort as he could.

He could feel the suckers against Alec’s skin, the way they were pressed so ardently there. The taste and feel of Lorenzo’s magic was a rancid familiarity but Magnus bore the burden bravely. It was better, to deal with it himself and suffer a brief discomfort as his magic purified and then banished Lorenzo’s magic than to have it stay in Alec’s core. He also couldn’t deny how protective it made him. After all, Lorenzo’s magic was a cheap power and who knew what it would do to Alec, left unchecked. 

The alliance rune was a different sort of magic but they’d played with magic enough in the bedroom that Magnus felt confident and comfortable with creating a strange sort of replica. 

His own magic trickled into Alec’s core gently, soothing over the burns left by Lorenzo’s power and coiling possessively there inside of Alexander. Now, when one of Magnus’ tentacles placed a sucker to Alec’s skin and nestled there, his body arched in response. Magnus’ fingers tightened as Alec moaned, the magic dancing through him with a fervent, giddy delight.

“Magnus,” Alec gasped out and Magnus obligingly caught him in a kiss before pulling away and letting him catch his breath. Alec’s shirt hung off his arms, catching where the tentacles were wrapped around his biceps but exposing his chest and torso and all the marks that had been left there. Magnus bent his head and pressed his lips to one on Alec’s collarbone, hiding a smile against the bruised skin at his fiancé’s shuddering breath and relishing the little moan it earned him when he soothed it with his tongue.

“That’s better, isn’t it?” He asked teasingly, dragging his teeth over one particularly vibrant and sensitive bruise. 

“Anything better if it’s you,” Alec said and Magnus had to stop what he was doing to look up and see how adoringly Alexander was looking at him. 

“I think they like me now,” Alec whispered with a happy smile, as though it were a secret for just the two of them.

Magnus’ tentacles bristled in indignation and he gave a weary, mental sigh. 

“They always liked you,” he tried to explain but he knew he was fast running out of time.

“Really? They sure didn’t seem like it.”

“Oh for the-” Magnus groaned and pressed his brow to Alec’s, “you’re not going to make this easy.” He warned, “they’re determined now.”

“Determined to do what?”

“Determined to prove that they love you. That every bit of them admires you as much as I do.” As Magnus spoke, his tentacles began to stroke delicately at the parts of Alec they knew to be most sensitive and Alec groaned, bucking up against Magnus. 

Magnus couldn’t help the titter he let out, or the way that he and his tentacles felt smug and prideful. He could also feel how one, sneaky tentacle that had been stroking Alec’s thigh in soothing, repetitive motions was changing. It’s suckers pressed to the tender, sensitive skin of Alec’s inner thigh and he laughed when Alec jolted from the feeling. 

“They’re quite thorough,” Magnus promised with laughter and Alec glowered, reluctant amusement filling his eyes.

“So they like me,” he shuddered as another pressed against him, “okay understatement. They  _ really _ like me, but how am I going to hide this many hickeys? It doesn’t even make sense!” 

Magnus grinned and nipped at a mark with smug satisfaction, “I’m sure you’ll figure something out,” he promised and set his teeth to adding another to the collection. 

**Author's Note:**

> I'm on tumblr as [alexanderlightweight](https://alexanderlightweight.tumblr.com)


End file.
